Cardiovascular System - The Vessels Flashcards
What is the general purpose of blood vessels?
- movement of blood from heart to periphery and back
- must resist pressure from heart
- must prevent backflow when pressure drops
- must provide transport to and from tissue as well as to and from lumen of vessel
- must regulate and respond to changes in pressure
Oxygenation depends on…
lungs
Difference in pressure explains….
difference in structure
What are generally thicker, arteries or veins?
Arteries
Define: Tunica Intima
Lining (endothelium) - barrier
inner most
continuous with epithelium of heart
think endocardium - lumen of vessel
Define: Tunica Media
Muscle (smooth) - alter lumen size
middle layer
think myocardium
Define: Tunica Adventitia
CT (dense/elastic) - support
outermost layer
think epicardium - adipose near
What layers make up the Tunica Intima?
Endothelium
Subendothelial CT
Internal Elastic Lamina
Vascular Regulation
Autoregulation
Vasodilators
Endothelial Secretions
Hormones
Myogenic Autoregulation
intrinsic contractile response of smooth muscle when stretched
Metabolic Autoregulation
low blood flow restricts vasodilator movement away from the tissue → accumulation
Define: Endothelial Regulation
provides continuity to prevent sheer stress
responds to shear stress, stretch, circulating substances, inflammatory mediators
Endothelial Cell Control
Important functional part of blood vessels
not just static lining
produce active compounds that affect smooth muscle and immune cells
Endothelial Regulators
Arachidonic Acid Derivatives
Nitric Oxide
Endothelial Regulators: Arachidonic Acid Derivatives
Prostacyclin (vasodilator)
Thromboxane A2 (platelet aggregation and vasoconstriction)
Endothelial Regulators: Nitric Oxide
vasodilator
Produced from arginine by nitric oxide synthase
activates guanyl cyclase; cGMP mediates relaxation of smooth muscle cells
What are the associated functions of maintenance of selective permeability barrier?
simple diffusion
active transport
pinocytosis
receptor-mediated endocytosis
What are the associated functions of modulation of blood flow and vascular resistance?
secretion of vasoconstrictors
secretion of vasodilators
What are the associated functions of regulation of cell growth?
secretion of growth-stimulating factors
secretion of growth-inhibiting factors
What are the Associated functions of regulation of immune response?
leukocyte mgration
What are active molecules involved in regulation of immune response?
interleukin
___ travel together
Similar-sized vessels travel together
How do you tell the difference between arteries and veins?
veins are more irregularly shaped
arteries are more round or oval shaped
arteries have a more muscular wall and are generally thicker
General Artery Description
thin tunica intima
thicker tunica media relative to similar vein
thinner tunica adventitia than similar vein
no valves
internal/external elastic lamina → more in arteries than veins
Why do arteries tend to not have valves?
pressure keeps blood moving forward
General Vein Description
Thin Tunica Intima
Thinner Tunica Media relative to similar artery
Thicker Tunica Adventitia than similar artery
valves
no internal/external elastic lamina
Why do veins have valves?
They need to keep blood from back flowing due to changes in pressure
Define: Vasculogenesis
Create → initial building/formation of new blood vessels
during development
from angioblasts in the embryo
Define: Angiogenesis
repair or replacement of blood vessels in response to injury/cancer
occurs in preexisting vessel
As vessels branch….
they get smaller
still have the same layers (until capillaries)
___ is the largest artery
___ is the largest vein
Aorta
Vena Cava
Why are the aorta and vena cava also known as the elastic artery (vein)?
due to substantial elastic fibers in t. media
What is the difference between the Aorta and Vena Cava and other large arteries/veins?
Other large arteries/veins will appear similar, but have thinner walls and smaller lumens
Other large arteries/veins are continuous with the medium (muscular arteries and medium veins)
Define: Aorta
Thin Tunica Intima
Thicker Tunica Media relative to the Vena Cava
Thinner Tunica Adventitia than Vena Cava
No Valves
Elastic Lamina throughout Tunica Media
Define: Vena Cava
Thin Tunica Intima
Thinner Tunica Media relative to aorta → smooth muscle is circular
Thicker Tunica Adventitia than aorta → smooth muscle is longitudinal
Valves
Internal Elastic Lamina → not in other veins
Elastic Fibers throughout media/adventitia
Muscular Artery (Medium Artery)
Elastic Fibers but not continuous
Tunica Media is same or thicker than adventitia
thin Tunica Intima
Elastic Lamella/fibers
Medium Vein
Tunica Adventitia thicker than media
no internal/external elastic lamina
bundle of smooth muscles
Small Artery/Vein vs. Arteriole/Venule
Similar Structure → no elastic lamina
travel together
arteriole/venule often seen near capillaries
Tunica Media Layers in Small Artery/Vein vs. Arteriole/Venule
Small Artery: 2-4
Small Vein: 1-2
Arteriole: 1-2
Venule: 0
Define: Capillaries
No Layers
Endothelium with basement membrane
occasional pericyte
Define: Pericyte
Supporting cell of capillaries
contractile
potential source of repair by acting like STEM Cell
Why does a venule stain lighter than an arteriole?
because the venule has no/less smooth muscle
Define: Continuous Capillary
continuous basal lamina
endothelial cells have a complete cytoplasm
closely resembles venule → smaller lumen
1 RBC or less
Define: Fenestrated Capillary
in areas where you want more diffusion across the wall
basal lamina is continuous
moe/absorb nutrients → nutrients, glucose
small intestines
Define: Discontinuous Capillary
Removes Cells
easier for things to move across the border
fewer tight junctions
basal lamina is incomplete
sinusoid
liver, spleen
Capillary Structure
- crossing the endothelium
- permeable → small hydrophobic → O2, CO2, simple diffusion
- Everything else
- Transported across cell → pinocytosis or fenestrations
- transported across junctions → zonula occludens or discontinuous
- basal lamina is different
Define: Lymph Vessels
Carry Lymph to lymph nodes from peripheral tissues
very thin wall → endothelium basement membrane
no RBCs in lumen
anchor to CT → not much wall structure
Valves of Lymph Vessels (and veins)
Core: CT
covered in endothelium
protrudes from wall → anchored to tunica media
unidirectional blood flow
Identify the Structure: Thick wall for size of lumen, large wall to lumen ratio, has internal elastic membrane visible
muscular artery
Identify the Structure: Thick wall for size of lumen, large wall to lumen ratio, no internal elastic membrane visible, elastic present within the media
elastic artery
Identify the Structure: Thick wall for size of lumen, large wall to lumen ratio, no internal elastic membrane visible, no elastic present within the media
small artery
Identify the Structure: Thin wall for size of lumen, Small wall to lumen ratio, Large vessel size
vein
Identify the Structure: Thin wall for size of lumen, Small wall to lumen ratio, small vessel size
venule
Define: Large Artery
- diameter → >10 mm
- Tunica Intima
- endothelium
- connective tissue
- smooth muscle
- Tunica Media
- smooth muscle
- elastic lamellae
- Tunica Adventitia
- thinner than tunica media
- connective tissue
- elastic fibers
Define: Medium Artery (Muscular Artery)
- diameter → 2-10 mm
- Tunica Intima
- endothelium
- connective tissue
- smooth muscle
- prominent internal elastic membrane
- Tunica Media
- smooth muscle
- collagen fibers
- relatively little elastic tissue
- Tunica Adventitia
- thinner than tunica media
- connective tissue
- some elastic fibers
Define: Small Artery
- Diameter → 0.1 - 2 mm
- Tunica Intima
- endothelium
- connective tissue
- smooth muscle
- internal elastic membrane
- Tunica Media
- smooth muscle (8-10 cell layers)
- collagen fibers
- Tunica Adventitia
- thinner than tunica media
- connective tissue
- elastic fibers
Define: Arteriole
- diameter → 10-100 um
- Tunica Intima
- endothelium
- connective tissue
- smooth muscle
- Tunica Media
- smooth muscle (one or two cell layers)
- Tunica Adventitia
- thin, ill-defines sheath of connective tissue
Define: Capillary
- diameter: 4-10 um
- Tunica Intima
- endothelium
- Tunica Media
- none
- Tunica Adventitia
- none
Define: Postcapillary venule
- diameter: 10-50 um
- Tunica Intima
- endothelium
- pericytes
- Tunica Media
- none
- Tunica Adventitia
- none
Define: Muscular Venule
- diameter → 50-100 um
- Tunica Intima
- endothelium
- Tunica Media
- smooth muscle (one or two cell layers)
- Tunica Adventitia
- thicker than tunica media
- connective tissue
- some elastic fibers
Define: Small Vein
- diameter → 0.1 - 1 mm
- Tunica Intima
- endothelium
- connective tissue
- smooth muscle (two or three layers)
- Tunica Media
- smooth muscle (two or three continuous with tunica intima)
- Tunica Adventitia
- thicker than tunica media
- connective tissue
- some elastic fibers
Define: Medium Vein
- diameter → 1-10 mm
- Tunica Intima
- endothelium
- connective tissue
- smooth muscle
- Internal elastic membrane in some cases
- Tunica Media
- smooth muscle
- collagen fibers
- Tunica Adventitia
- thicker than tunica media
- connective tissue
- some elastic fibers
Define: Large Vein
- diameter → >10 mm
- Tunica Intima
- endothelium
- connective tissue
- smooth muscle
- Tunica Media
- smooth muscle (2-15 layers)
- collagen fibers
- Tunica Adventitia
- much thicker than tunica media
- connective tissue
- some elastic fibers, longitudinal smooth muscles
- cardiac muscle extensions (myocardial sleeves) into great veins near the heart
